Pear Tree with Spotted Leaves - Ask Extension
Hi, I just planted a new pear tree last summer and when I went to check on it now that it is leafing out, I found a few leaves that had brown spots. I...
Knowledgebase
Pear Tree with Spotted Leaves #867020
Asked May 04, 2024, 2:11 PM EDT
Hi, I just planted a new pear tree last summer and when I went to check on it now that it is leafing out, I found a few leaves that had brown spots. I am wondering if this is some sort of fungus? How should I treat it? How could I have prevented it and prevent in the future?
Thanks so much.
Boulder County Colorado
Expert Response
Hi Erin,
Thank you for writing to us about the problem with your pear tree. Based upon photos you sent, it appears you could be dealing with leaf blister mites. The only way to be certain is if you could bring a leaf sample in for us to test and view under a microscope.
Blister mites are extremely small, almost microscopic in size. On pear trees, they first appear as small greenish pimples that become reddish, then brown. They may cover the lower leaf surface.
Adult blister mites enter bud scales in August to September to overwinter. They become active at bud break, migrate to the tender, new leaves, and burrow beneath the epidermis of the underside of leaves to feed. This results in a gall, or blister, in which the eggs are laid. The nymphs remain in the blister, emerging as adults to migrate a short distance and form new galls.
If you'd like to bring in a sample leaf from your pear tree, the Extension office is located at 9595 Nelson Road in Longmont. We are at the corner of Hover and Nelson Road.
The first two samples are free to Boulder County residents. For non-residents, the fee is $4.00 per sample.
Regards,
CSU Extension Boulder County
Colorado Master Gardener
Thank you for writing to us about the problem with your pear tree. Based upon photos you sent, it appears you could be dealing with leaf blister mites. The only way to be certain is if you could bring a leaf sample in for us to test and view under a microscope.
Blister mites are extremely small, almost microscopic in size. On pear trees, they first appear as small greenish pimples that become reddish, then brown. They may cover the lower leaf surface.
Adult blister mites enter bud scales in August to September to overwinter. They become active at bud break, migrate to the tender, new leaves, and burrow beneath the epidermis of the underside of leaves to feed. This results in a gall, or blister, in which the eggs are laid. The nymphs remain in the blister, emerging as adults to migrate a short distance and form new galls.
If you'd like to bring in a sample leaf from your pear tree, the Extension office is located at 9595 Nelson Road in Longmont. We are at the corner of Hover and Nelson Road.
The first two samples are free to Boulder County residents. For non-residents, the fee is $4.00 per sample.
Regards,
CSU Extension Boulder County
Colorado Master Gardener
I had someone else say they thought this was also the case. Do you have a suggestion on treatment? Or that is needed? Remove the leaves?
ᐧ
Hi Erin,
Without having a physical sample, we can only go so far as to suggest what may be wrong, in this case possibly blister mites. If you have an opportunity to bring in a physical sample of the affected leaves, our Diagnostician team can confirm with certainty what is affecting the plant.
If it IS blister mites:
Remediation of blister mites involves treating the infestations in fall before leaf drop when mites are migrating from leaves to buds with carbaryl, horticultural oil or lime sulfur. Applications can also be effective in spring, but the mites cannot be treated in summer because application of dormant oil could seriously harm your pear tree. Depending on the severity of the infestation, it may take a year or two of treatment for the tree to fully recover from the infestation.
We hope this helps.
Regards,
CSU Extension Boulder County
Colorado Master Gardener
Without having a physical sample, we can only go so far as to suggest what may be wrong, in this case possibly blister mites. If you have an opportunity to bring in a physical sample of the affected leaves, our Diagnostician team can confirm with certainty what is affecting the plant.
If it IS blister mites:
Remediation of blister mites involves treating the infestations in fall before leaf drop when mites are migrating from leaves to buds with carbaryl, horticultural oil or lime sulfur. Applications can also be effective in spring, but the mites cannot be treated in summer because application of dormant oil could seriously harm your pear tree. Depending on the severity of the infestation, it may take a year or two of treatment for the tree to fully recover from the infestation.
We hope this helps.
Regards,
CSU Extension Boulder County
Colorado Master Gardener
